FMDV causes a livestock disease with significant economic impact in endemic regions where it currently circulates. Furthermore, FMDV has the potential for great economic damage were it to be introduced into FMDV-free areas. Current “kill, burn, and bury” outbreak control strategies are unsatisfactory for economic, humane, and strategic reasons (Breeze, Biosecur Bioterro 2(4): 254-264, 2004). Although vaccination could be an integral part of outbreak management, available vaccines, which are based on inactivated virus, are unsatisfactory in terms of cost, production safety, duration of immunity, and breadth of protection (Rodriguez and Gay, Expert Rev Vaccines 10(3):377-387, 2011; Robinson et al., Transbound Emerg Dis 63 (Suppl 1):30-41, 2016. Outside of North America, the European Union, Australia and New Zealand, FMDV circulates widely. FMDV is durable in the environment and highly infectious. The direct economic impact of an FMDV outbreak in the U.S. is estimated at tens of billions to hundreds of billions of dollars, with rapid and extensive vaccination possibly reducing the cost by one-half (Schroeder et al., Journal of Agricultural and Applied Economics 47:47-76, 2015).
FMDV has seven major serotypes, four that are widespread (A, O, C, and Asia-1), and three predominantly found in sub-Saharan Africa (SAT-1, SAT-2, and SAT-3). Within-serotype diversity is high, and there is little cross-protection even between isolates of the same serotype. In view of this diversity, each outbreak needs to be field-matched to one of many vaccine strains. Recent developments in FMDV vaccines have led to improvements in many areas (Robinson et al., Transbound Emerg Dis 63 (Suppl 1):30-41, 2016), but breadth of protection is still limited; most vaccines only protect against outbreaks closely related to the vaccine strain, so protection against all possible outbreaks would require prohibitively large stockpiles.
Thus, a need remains to improve the breadth of vaccine-induced protection from different strains of FMDV.